Could be vacuum leak. if the rough idle comes and goes (intermittent), it could be the EGR. I just replaced the EGR on my 2001 F150 5.4L. When it got below freezing, the truck would stall as well.
"Owners of some 1997-2005 Ford Trucks with the 5.4L two-valve engine may complain of an intermittent rough idle. One likely cause, says Ford, is noncommanded EGR flow. A stuck open EGR vlave is ultimately the culprit.
To make a definitive diagnosis, connect your scan tool, start the engine and allow it to reach normal operating temperature. Next, allow the idle to stabilize, scroll down to the DPFEGR PID on the scanner's display and write down the voltage. Now disconnect the vaccuum hose to the EGR valve and connect a vaccuum pump to its port. Pump the vacuum up until the EGR valve is wide open, then bleed off the vaccuum. Record the DPFEGR voltage again. Repeat this procedure several (about 8) more times.
If the DPFEGR voltage increases by .03 volt or more from the initial reading and the idle gets rough, the EGR valve is probably stuck open. Try tapping the casting with a wrench. If the voltage decreases and the idle now gets smooth, the valve is definitely sticking. Replace it with a revised design, Part No. XL3Z-9D475-CA.
Trucks that can benefit from the upgraded EGR vlave are 1997-99 F-250 light duty pickups, 1997-2004 f-150s, 1998-99 Lincoln Navigators, 1997-2005 E-series vans, 1998-2004 F-super duty pickups and 2000-05 Excursions."
Spark Plugs have to be changed every 3 years
Front Oxygen Sensors changed every 100,000 miles
Can't have any Vacuum Leaks -- anywhere on the vehicle
Need to have it road tested with a Professional Scan Tool
& look at all data & get caught up on Preventative Maintenance
Very few people change motor oil 3 or 4 times a year, if at all,
and the Variable Cam Actuators fail, as a result,that & few other
things can cause rough running engine & resulting idle issues
It's well known that Ford COP Ignition Coils fail sometime in
every year of ownership
It can be issue
with IAC( idle air control valve) causing the problem.
There
are many other possibilities causing these idle issues.Engine idles rough.
There
are few help links with solutions to troubleshoot such idle issues.
I
suggest you refer the link below and follow
its troubleshooting details:------
Click
the link below:-----
Bad miss at idle?
http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html
-----------
Stumbling and stalling at
idle after engine rebuild?
http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html
------------
1999 Ford F-150 Idles rough and quits when gas
pedal is pressed less?
http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html
---------
Engine stumbles coming off idle when warm?
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------------
Erratic idle on car?
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
-----------
Cold start problem and vehicle shudder around 2500 to
3500 rpms
http://repairhelpcenter.blogspot.com/2012/10/cold-start-problem-and-vehicle-shudder.html
----------
Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
-----------
GMC Sonoma Stalls and idles low
http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html
--------
GMC Idle Air Control (IAC)
Valve Replacing?
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html
-------------
1996 Camry intermittent
engine failure while idle?
http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html
------------
Engine quits at idle?
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
-----------
Car overheats and Air blows
hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
---------
High
Idle Problem
http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html
-------
While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------
Idle flair is noticed on car? Rough idle? car
will not idle? Erratic idle speed?
http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
--------
High rpm in neutral? Inconsistant high RPM in
neutral?
http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
-------
Vehicle stumbling at idle
and shows code 54?
http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html
----------
Rough idle, staling and Erratic shifting?
http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html
-----------
While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------
These
details will help.
Thanks.
http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
-----`-
2006 kia rio runs rough
http://technoanswers.blogspot.com/2012/10/2006-kia-rio-runs-rough.html
-----------
Idle flair is noticed on car? Rough idle? car will not idle?
Erratic idle speed?
http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------
Rough idle, staling and Erratic shifting?
http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html
---------
These details will help.
Thanks.
http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
---------
will not idle when cold?
http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
----------
runs lean and idles rough?
http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------
Engine stumbles coming off idle when warm?
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------
Erratic idle on car?
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
----------
Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
---------
Idle Air Control (IAC)
Valve Replacing?
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html
-----------
Replace
Idle air control valve?
---------
Test
Idle Air Control (IAC) Valve?
-------
Idle
Air Control (IAC) Valve operation?
----------
Engine quits at idle?
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
------------
Car overheats and Air blows
hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
------
While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------
This will help.
Thanks.
http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
---------
will not idle when cold?
http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
----------
runs lean and idles rough?
http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------
Engine stumbles coming off idle when warm?
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------
Erratic idle on car?
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
----------
Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
---------
Idle Air Control (IAC)
Valve Replacing?
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html
----------
Engine quits at idle?
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
------------
Car overheats and Air blows
hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
------
While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------
This
will help.
Thanks.
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
------------
Car
overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
------While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------This will help.Thanks.
http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html
-----------
Nissan Pathfinder Backfires?
http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm?
http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000
RPM?
http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.
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